The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Wind power is the process by which the wind is used to generate electricity. Wind turbines convert the kinetic energy in the wind into mechanical power and a generator then converts this mechanical power into electricity.
Wind turbine blades are exposed to a variety of adverse conditions and a wide number of airborne objects. These may include, but are not limited to rain, ice droplets, dust, bugs, bats, and birds. Blade wear comes from multiple sources including: erosion, impacts, and lightning. Blade wear is proportional to the relative velocity of the blade. Modern large scale turbines operating at their nameplate power can have a blade tip speed approaching 200 MPH.
Wind turbine blades can account for 15-20% of the total cost of a turbine system, and are the most expensive components to repair in situ. Blades are complex and expensive; a 35-meter blade can cost $150,000 excluding shipping and installation. Blade maintenance makes up a large portion of the maintenance of a wind turbine. Data from European wind farms suggests that blades have the highest failure rate of all the complex systems of a wind turbine and that blade failures result in extended down times.
Erosion of the leading edge of wind turbine blades is generally considered to be the distributed wear of blade caused by airborne particles. These elements can erode the leading edge of a turbine blade, resulting in an increase in surface roughness and a decrease in power production. Lightning strikes tend to contact the tips of the blades, and can result in fires and other catastrophic failures of the entire wind turbine system.
Impacts or strikes to wind turbine blades can cause localized damage. This damage, like that of erosion, can cause an increase in surface roughness and a decrease in power production. Additionally, impacts can cause the loss of blade material creating a rotating mass imbalance that can cause catastrophic damage to the whole turbine system if left unrepaired. By far, the greatest sources of impacts are of the avian kind. The U.S. Fish and Wildlife service estimates the potential for about 30,000 bats strikes per year in the state of Illinois alone.